Difference between rolling resistance and tractive force

[sganesh88]

It was just simple what i asked in the beginning but u made it this thread too long due to misconceptions(e.g action reaction and friction forces are different force pairs) and u also gave wrong directions of tractive force and RR. Please don't mind.

Cool. People can misunderstand your question. Happens all the time. And what if the thread gets too long? The end result is we need to understand the concept clearly.

1.Does friction due to tractive force helps in stopping the wheel apart from RR?

Tractive force's nature is frictional. Generally we refer Tractive force as the one that makes the vehicle accelerate. (though the same friction helps the vehicle to decelerate too. Its all semantics) Even if the engine stops giving power to the wheels, its the combined effect of internal friction, air resistance, gradient resistance and rolling resistance at the wheels that will bring the vehicle to rest. Not the tractive force.

2.Why direction of RR is in backward direction? Since it generates an anti spin torque due to displacement of normal reaction as a result of tyre deformation so direction of RR should be forward same as that of tractive force.

Torque decelerating the tire's rotation needn't always be due to a force in the forward direction. It can also be in the vertical direction. Its the normal force that contributes to the resistive moment. Thats why i said in one of my posts above that in a frictionless surface, rolling resistance moment cannot reduce the velocity of the vehicle *much* as the horizontal component of the normal force is negligibly less. Rolling resistance involves loss of energy due to hysteresis but deceleration of the vehicle due to friction. Just like kinetic friction at the brake pads produces an energy loss at the wheels and static friction brings about deceleration of the vehicle during normal braking.

3.How to calculate it. I mean friction due to tractive force= u N
then what is RR=?

refer:
http://en.wikipedia.org/wiki/Rolling_resistance#Physical_formula

 

[R Power]

1. clear o.k.
2. Unclear
Imagine wheel rotates in clockwise direction
U say that RR is due to normal component basically due displacement of normal component. So, normal component is displaced a bit forward(in the direction of motion), so as to provide an anti spin torque and also because tyre deforms at the front where it first pushes the ground. So this torque will be in upward direction (as displaced normal force) which will be opposite to wheel rotation, then how can it's direction be backward which is clockwise (i.e direction of wheel rotation).
3. Clear

BTW u r from India i guess! Me too!

 

[sganesh88]

So this torque will be in upward direction (as displaced normal force) which will be opposite to wheel rotation, then how can it's direction be backward which is clockwise (i.e direction of wheel rotation).

Answer this question. When we apply brakes, what is the flow of processes that end up in decelerating the vehicle?
Ya i am from India. :)

 

[R Power]

When we apply brakes friction is produced between brake shoe surface and tyre which gives an anti spin torque to decelerate.
All the kinetic energy of wheel gets converted into heat energy.